Caption: Black smoker vent. The plume of blackened water (centre left) comes from a newly formed hydrothermal vent or "black smoker". This is an opening on the sea floor where superheated, mineral-rich water is emitted due to volcanic activity. The black rock at far left is recently cooled lava from the eruption which created the vent, hours or days earlier. The rock at right appears white due to bacterial growth. This image was taken from the Woods Hole Oceanographic Institute's ALVIN submersible. Photographed in 1991 on the East Pacific Rise, a mid-ocean ridge region where magma rises from the earth's crust due to spreading tectonic plates.